Temperature and relative humidity: What they mean for you and your concrete countertops

Posted on May 11, 2012 by Jeff Girard

Drying is an important process that must be managed and understood in order to avoid problems. At certain times drying is to be avoided, whereas at other times it is necessary. Understanding how temperature, dew point and humidity levels work together will shed light on how you can manage drying.

Concrete needs to stay moist in order for it to cure. But some sealers need the concrete to be dry in order for them to cure and stick properly. It’s a delicate balance. Temperature and humidity levels play a major role in whether your concrete or sealer cures properly, or whether your concrete stops curing, develops map cracking (or worse) or if your sealer has bonding and curing problems.

It’s well known that in hot conditions things dry out fast. So during the summer months (and for some of us summer temperatures have already arrived) it’s vital to make sure bare, exposed concrete that’s still curing stays moist. On the other hand, cold temperatures make it harder to dry things out. Cold concrete takes much longer to dry out because water does not evaporate as fast.

I will describe how drying is influenced by temperature, relative humidity and describe what the dew point is and how it relates to relative humidity.

Drying is also known as evaporation. The rate at which water evaporates depends upon several factors, including the temperature, relative humidity and air flow rate. Water evaporates very fast when it’s exposed to hot, dry fast moving air. Conversely water evaporates very slowly when it’s in cold, damp still air.

Temperature describes how much energy is available to drive evaporation. On a warm day more water can evaporate because there is more thermal energy available to do the work of evaporation. In contrast water has less available thermal energy to drive evaporation when it is cold out. Hence drying slows considerably when it’s cold.

Relative humidity is important because the more moisture that’s already in the air, the lower the rate at which water will evaporate and the less moisture that the air can hold.
Relative humidity is a measure of the current amount of water vapor in the air relative to the total amount of water vapor that can exist in the air at its current temperature, and is expressed as a percentage.

A relative humidity of 100% means the air cannot contain any more water vapor at that temperature, whereas a relative humidity of 50% means that the air only has only half as much water vapor as it can hold at the current temperature.

Dew Point is the air temperature at which the air is saturated with water vapor. Warm air can “hold” more water than cold air. When air at a given temperature can’t hold any more water it is fully saturated and is at 100% relative humidity. The air isn’t holding onto the water vapor. What’s being described is really the temperature when water vapor levels reach the saturation point.

Air flow rate is important, because as water evaporates, the layer of air above the water (or damp concrete) gradually becomes more saturated with water vapor. When evaporated moisture levels reach saturation drying essentially stops. Air flow increases the evaporation rate by “flushing” away the stagnant moist air above the concrete.
The following graph shows the relationship between air temperature, dew point temperature and relative humidity.

Moist Curing
Concrete needs to remain moist in order for it to cure. Generally the internal relative humidity needs to be above 80% to 85% relative humidity for hydration to take place.

Wetting the surface of bare concrete creates a barrier of water that prevents the moisture from inside the concrete from being drawn out when the surface moisture evaporates. The film of water on the surface is a relatively large reservoir that can evaporate without affecting the moisture within the concrete’s pores. Water on the concrete acts like a buffer.

When concrete is covered in plastic, the air trapped under the plastic quickly becomes saturated with water vapor. When this happens drying essentially stops.

When concrete dries out, the suction forces developed when water evaporates from the pores in the concrete can actually crush weak cement paste. The longer the concrete remains moist, the greater its strength and the greater the resistance to the suction forces. This means fewer cracks and less shrinkage and curling. Longer wet curing also reduces pore size, which means less moisture is available to evaporate and that the moisture has a harder time escaping out of the concrete.

Drying
Some sealers need concrete to be dry in order to stick properly. And some sealers will not cure properly if there is too much moisture in the concrete.

Temperature and relative humidity are important factors to pay attention to so that your concrete dries to the degree you need it to so that the all-important sealer performs the way you and your client expect it to.

If your shop is cold (like most shops are in the winter), the evaporation rate is slower, and because most shops have open sources of water in them (trench drains, wet grinding areas, etc.), the relative humidity is generally higher than outdoor conditions. These limit how much drying occurs. If your shop is at 100% relative humidity it doesn’t matter how long you “dry” the concrete. It won’t lose moisture and dry out because the air surrounding the concrete can’t hold any more moisture.

Remember: wet concrete doesn’t dry out in small, cold shops with still air. Hot shops with moving air that has a low relative humidity will cause rapid drying.

Happy concreting!

Concrete countertops in India

Posted on April 9, 2012 by Jeff Girard

I recently had the privilege to visit Bangalore, India to train someone on how to make concrete countertops. To my knowledge, this is the first introduction of concrete countertops to India. The student, Ajaay Srinivaas, is a successful business person with a tile importing business and an incense business, and has now created Nuance Studio to offer concrete countertops, sinks and elements. I will write a more thorough account of Ajaay’s company later, but for now I want to share a few photos of my trip.

Before the trip, I had Ajaay acquire all the tools and materials he would need. This was a challenge, as the types of tools and materials available in India vary widely from the U.S. For example, we had trouble finding foam rollers for applying sealer. There are no Home Depot or Lowes stores. Here is a photo of the local hardware store.

Indian hardware store

However India does have several good brands of portland cement.

Most of the items Ajaay imported from the U.S. These should look familiar to you.

And this too, although usually you don’t see flowers on a miter saw! The day I arrived was the Ugadi new year festival, and all the machines were blessed with flowers and greenery.

India was the most exotic place I’ve traveled to so far. It was amazing! Cows really do roam the streets. I couldn’t get over that.

This cow walked by next door to the shop. She wanted to help make concrete!

And the traffic is harrowing – constant honking, swerving, tailgating, with cars, trucks, buses, rickshaws, motorbikes with whole families on them, pedestrians and cows all mixed in.

My wife Lane had a fabulous time shopping. The clothing and fabrics were stunningly beautiful, and there were lots of treasures to be found.

We visited a palace and a Hindu temple and rode an elephant!

It was an amazing experience. There are lots more photos on the CCI Facebook page.

I look forward to seeing lots of photos of Ajaay’s future concrete creations. Thanks Ajaay for a great experience!

ERO Decorative Concrete Builds Creativity on a Solid Technical Foundation

Posted on March 12, 2012 by Jeff Girard

Erik Oftebro, a native of Santa Barbara, CA, has always loved working with his hands. He has transitioned from training horses at the family ranch to structural concrete, and finally landed in the decorative concrete industry. His passion for making beautiful concrete started when he was doing a job for a Harley Davidson shop near Sacramento which called for decorative concrete, a method he had been unfamiliar with. Once he started, he couldn’t get enough! He was inspired to get his concrete contractor’s license and went into decorative work full time as ERO Decorative Concrete.

Eventually, he decided to expand into the realm of concrete countertops, an area which he had known about, but hadn’t had a lot of hands-on experience in. He came to the CCI Ultimate class in March of 2011 and never looked back.

Erik loves the innovative possibilities inherent with concrete, especially in Santa Barbara, where people are ready to embrace new ideas and are excited to try new ways of doing things. He loves opening people’s eyes to the fact that concrete isn’t just this gray stuff (although it’s amazing how many people do prefer the ‘raw’ gray look), but is ripe with potential. The key is in making good concrete first, pretty concrete second. Once you know the principle foundations for making quality work, you can tailor the actual project to whatever the customer wants.

He had a project recently where a family was moving into a new home and wanted a custom stair case and landing that would match their countertops. The spiral staircase had 11 treads that had to be cast individually, since each was slightly different from the others. One of the daughters in the family won a fight with cancer, and the family commemorated the occasion by adding names and hand prints to one of the stair treads. Details like that really make concrete projects stand out to the average home owner.

The landing was the challenging bit, since it was four feet across, three feet wide, had an inch ledge on two sides, and was unsupported on another. It also had a curve that had to fit flush against the wooden flooring. Quite a challenge! Erik was able to work with Jeff Girard to make sure he was creating a beam that would support the weight without cracking.

Erik Oftebro stair landing

Staircase landing flush with wood floor

Erik Oftebro stair treads

11 stair treads, all different sizes

Another recent project came from a referral by the general contractor in charge of a remodel; Erik’s name was mentioned and the client looked him up via the CCI Find a Contractor Listing. The client had a stone wine cellar that had a travertine bar. She didn’t like the striated look of it, and had thought about getting the piece done in limestone, but it would not have fit in with the aged look of the rest of the space. Erik was able to make a few samples until he found one the customer loved. He created a slab with travertine as the inspiration, and installed it raw into the space. He was then able to custom match a stain that gave the piece the same patina of the rest of the room, combining new and existing features seamlessly. The client was thrilled with the result, and has since commissioned several more projects.

Erik says it’s very satisfying to be able to accept a client that a lot of contractors would walk away from. Whether it’s someone who wants stair treads that match their counters, a sandstone-looking BBQ surround, or a vanity that is created to match a favorite picture, it’s a never ending challenge. There will always be ways to think outside the box.

He is very thankful that he put the investment in to learn the basic principles of concrete from Jeff. He has never had a callback about a quality issue, and that is mainly thanks to Jeff’s solid technical teaching. He is able to take what he knows and use it to build whatever the customer wants, and to get it right the first time out. That confidence in his own skill has enabled him to take the basic tools he learned at CCI and turn them into a success story.

Concrete Countertops Are Not Decorative Concrete

Posted on March 8, 2012 by Jeff Girard

But wait, you say. Concrete countertops are decorative and they are made of concrete, so that makes them decorative concrete, right? Well, not exactly. All right, so what is decorative concrete, and how is it different from concrete countertops?

Decorative concrete encompasses a wide variety of surface finishes and treatments that are applied to or performed on a base of ordinary concrete. By and large, decorative concrete transforms or alters the appearance of plain concrete to enhance the look by adding color, patterns and texture. Other than stamped concrete, most forms of decorative concrete are applied to or performed on pre-existing plain concrete. These include acid staining, decorative overlays, scoring, etching, micro-toppings, sandblasting, dying and polishing. More often than not, decorative concrete includes flatwork, such as floors, driveways, sidewalks and patios, and also includes vertical walls, faux stone and trees.

Concrete countertops often include elements used in decorative concrete. The obvious are integral pigments, acid stains and polishing. They also can be stamped, etched, scored and sandblasted. It is for these reasons that many people include concrete countertops in with the decorative concrete industry. However, the appearance of concrete countertops is only a part of what they are, whereas the appearance is essentially everything with regards to many forms of decorative concrete.

If they don’t fall completely within the decorative concrete industry, where do they belong? The answer is in the kitchen and bath industry. After all, concrete countertops are countertops that just happen to be made out of concrete. All of the factors, considerations and expectations associated with other high end countertop materials directly apply to concrete countertops.

dc diagram resized 600
Concrete countertops are not floors that have merely been reshaped and elevated to sit upon cabinets. They should not be treated like floors, because countertops in general are held to higher standards than floors. Client expectations of what a countertop should look like, how it should perform and the general design and functionality are all very different from floors.

Bad resized 600 This is what happens when you don’t respect the differences
between floors and countertops.

The same standards clients hold granite and other natural stone countertops to are applied just as rigorously to concrete countertops. It is for these reasons that concrete countertops mainly belong in the kitchen and bath industry, because their primary purpose and functionality are as countertops. The decorative part, while important, is secondary. Concrete countertops are not decorative concrete. Concrete countertops are countertops.

Challenges Specific to Concrete Countertops

The reality is that making high quality concrete countertops is far from simple. There are two main reasons for this: countertops and concrete.

Any countertop professional knows that making high quality countertops involves many details that represent challenges in planning the project, making the countertop itself and installing the countertop. It’s important to recognize that countertops are beams. Without proper reinforcement, the countertop is doomed to failure.

beam principal

Creating a high quality countertop begins with creating a high quality template. There are many templating techniques and even sophisticated computer systems to create templates. When templates are made, many considerations come into play, including planning overhangs, lining up seam locations with cabinet seams, placing sinks and faucets and more. Templating and planning all of these elements is a crucial step that most homeowners are either never told about or don’t understand the importance of.

Making any type of countertop involves a great deal of precision to ensure that the completed pieces match the template perfectly, and will therefore fit into the space. Every detail is important: the location of finished edges, the straightness and smoothness of the tops, the precision of the adjoining slab edges, even thickness of the slabs, etc.

Assuming the template is perfect and the countertops are precisely crafted to match the template exactly, the countertops still need to be installed properly. There are myriad important details that add up to a good installation: how to mount an undermount sink between the cabinet and the countertop, how to caulk between countertop and undermount sink for water-tightness and which caulk to use, how to secure the dishwasher, how to shim and adjust to make sure that seams are flush, and much more. This is after the slabs are safely transported into the kitchen or bathroom – that is a feat in itself that often requires specialized equipment. Check out a class video here:

Bottom line? Concrete countertops are in a league all their own, and it’s important to respect that. There is a great deal to understand about concrete and about countertops. Quite often people say, “But it’s all just cement and water, right?” Wrong. Dangerous oversimplifications and not taking the unique challenges inherent in concrete countertops often cause unsuspecting homeowners to bitterly regret their choice of material (and their contractors!).

The Concrete Countertop Shop: Business Strategy 101 Part 2

Posted on February 13, 2012 by Jeff Girard

Insider knowledge that will help you SELL your concrete countertops.

Relationship Marketing: the best tool you can use to build a successful business.

Remember that even if you have concrete that never cracks, is very stain and damage resistant, and looks great every time, you must be able to market it effectively; all the quality in the world doesn’t matter if no one sees it. This is where relationship marketing comes in. Relationship marketing is the art of networking with the influencers who will help you sell more product. In the case of concrete countertops, kitchen designers are the most powerful influencers.

relationships

Think about it. How many friends and family do you know right now who are remodeling their kitchens? None? One? Five? So if someone had made a beautiful concrete countertop for you and you wanted to give them a glowing referral, you would have maybe one to five people to refer them to. How many people do you think a kitchen designer knows who are currently remodeling their kitchens? Probably 50 or more. So who is the better source of referrals?

Let’s back up and talk a little about what a kitchen and bath designer is. A kitchen and bath designer is an educated professional who understands how to combine all of the elements of a kitchen or bathroom for a workable, livable space. (As shorthand, I generally use the term “kitchen designer,” but most of these professionals also design bathrooms.) Kitchen designers understand cabinets, countertops, sinks, faucets, appliances, floor finishes, lighting, tile and other design elements. They are like general contractors for the kitchen, and in fact some kitchen designers are actual general contractors.

Kitchen designers have showrooms where they display the cabinet, countertop, fixture and appliance brands they carry in appealing vignettes to help the customer make selections. They also keep a library of samples.

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The ultimate goal is to get your concrete countertops displayed in the high-end kitchen and bath showrooms in your area, creating a virtual sales force for your product. But before you can do that, you need to develop relationships with these professionals. Kitchen designers need to have confidence in you and your product, to know that you are going to do a good job for their clients. These relationships give you a dramatic advantage over any competitor who is not utilizing available connections and networking opportunity.

Partner Step by step….

If you are just starting out in the countertop business, the prospect of getting displays in these fancy showrooms may seem daunting. But it all starts with a simple phone call, with the modest goal of getting an appointment. Kitchen designers want to keep up to date on all the latest products. They will be happy to receive a phone call simply introducing your company and asking if you can show them some samples. Usually they will agree to a quick meeting, but even if they don’t, they will likely agree to let you drop off some samples and a brochure.

When you get a meeting with a kitchen designer, you have three goals:

make a good impression
leave samples
educate

If the outcome of the meeting is that they are confident in you and your product, they will agree to keep the samples and show them to potential clients.

kitchen design show

Once you’ve done a good job on a few projects with a kitchen designer, he or she may want you to install a display in their showroom if they have space. Be aware, though, that even if you leave samples or install a display, kitchen designers will not actively sell concrete countertops unless they understand them. In larger kitchen and bath showrooms, there are often multiple designers who work for a vice president of sales. You may have convinced the vice president of sales to put a large, prominent display in the showroom, but if the individual designers are not educated about concrete countertops, they will steer customers away. Make sure that you educate all the designers, and check in at least once per quarter to see whether there are any new designers and to give them samples of new colors, new edge styles or updated brochures. Maintain the relationship.

There are lots of other ways to develop and maintain relationships with kitchen and bath designers, as well as other design professionals such as interior designers and architects.

You can network at meetings held by the National Kitchen & Bath Association or the American Society of Interior Designers
have a grand opening of your shop
present to architects at lunch-and-learns

The same principles apply: Find the influencers, network with them to develop a relationship, and educate them so that they will feel confident in you and your product.

The power to create a successful, thriving business fabricating AND selling concrete countertops is within your grasp. Develope your website, get some materials to hand out, and go meet people who can influence your local market. What are you waiting for?

If you’re still a little uncertain about the details, get the 132-page book on How to Market and Sell Concrete Countertops, including actual call scripts for contacting kitchen designers.

The Concrete Countertop Shop: Business Strategy 101 Part 1

Posted on January 13, 2012 by Jeff Girard

Insider knowledge that will help you SELL your concrete countertops.

Concrete countertops are countertops. They just happen to be made out of concrete.

This fact should dictate your marketing and selling techniques: if you understand how countertops are most commonly and most effectively marketed and sold, you will be much more successful at marketing and selling concrete countertops.

1940salesman

This is not to say that concrete countertops being made from concrete is an unimportant or irrelevant fact. Concrete is, after all, the irreplaceable aspect that makes concrete countertops so beautiful, versatile and unique! It also pushes them into the high-end market, since they are custom-made from-scratch for each client. It doesn’t get any more homegrown and original than that! But keep in mind: these properties are merely great features of these particular countertops. Universal countertop marketing principles still apply.

Let’s get practical.

High-end countertops are most commonly used in kitchen and bath remodeling projects, or in truly custom new homes. Large developments with cookie-cutter or semicustom homes are unlikely to use high-end countertops, since they want to use something cheap, fast and with broad appeal. Typically they are not interested in quality, character or craftsmanship.

Knowing this, think about how homeowners buy high-end countertops. They don’t buy them from a large builder like Centex. They don’t buy them at Home Depot. They seek out the countertop fabricator themselves, or they use an interior/kitchen designer to help them.

6x4 BB Consultant Shot 1 resized 600

Let’s talk about the tools you need in your sales toolkit.

When seeking out a countertop maker, high-end countertop buyers (including the people you really want to work with: designers!) use the Internet to search. They do not use the phone book, except perhaps to find a plumber in an emergency. A website is one of the most important marketing tools in your arsenal. It can serve as an electronic brochure, portfolio and information source. It lends credibility and professionalism to your company. And it can generate leads for you.

A good website for high-end countertops needs only a few pages:

a home page

a contact page

an About Us page

a portfolio page

a product information page

The product information page is particularly important with concrete countertops, since novices tend to think of concrete as either looking like a public parking garage or being supernaturally immune to scratches, stains and general wear & tear. This is your chance to answer common questions such as “Does concrete stain?” and “Will it crack?” which will help prequalify your leads AND let potential clients see that you know what you’re talking about— if people can find it.

If you create a website without listing it, nobody will ever see it! It’s the equivalent of sticking a sign in your back yard–no one is going to see it unless you invite them over and point it out. That is why you need to use a contractor listing service; it’s like having an ad at the Superbowl. What you need is steady traffic stopping by your website, and the best, most reliable way to get that is through a listing service.

Now. A website is essential, but it’s a passive, impersonal form of marketing. So are print ads. I do not ever recommend print ads for startup concrete countertop businesses because they are so expensive in comparison to their rate of return. You will have many ad sales representatives trying to sell you print ads by saying, “One job per month could pay for the monthly cost of the ad.” Your response to that should be, “Why spend 100% of the proceeds from a single solitary job when I could be getting MORE jobs for a fraction of the ad costs by NOT using print ads?”

Carefully consider where you want your advertising budget to be–don’t make the rookie mistakes of spending all your money on useless ads that no one is going to see. It’s all about shooting at targets; if you don’t know what your targets are, you are shooting blind and you’re not going to hit the mark. 1154333866 1

Unless you have Ninja superpowers, this is not the way to go. Knowing who you are selling to (your target market) is absolutely essential to every successful marketing strategy.

No, in order to be truly effective at marketing concrete countertops, you need… (drum roll please)…. relationship marketing.

To be continued….

Golf shop concrete countertop makes a big impact

Posted on November 28, 2011 by Jeff Girard

When the owners of a golf shop approached Tony Angell to create a concrete countertop for their store remodel, they originally wanted just a plain, black countertop. That would have been fine, but not much of a challenge for Tony and not much of a focal point for the store. Instead of just settling for an average project, Tony turned this into a showpiece for both him and the golf shop. Here’s how he did it.

The owners were friends of the family, and familiar with the quality of Tony’s work in his Hugo, Minnesota based company, North Metro Concrete and Countertops. When Tony suggested getting creative, they said, “Go for it. We trust you.” And Tony did. The finished countertop incorporates the store’s name, a green, a water hazard, a sand trap, two golf clubs in the traditional crossed pose, a golf ball, blades of grass and a tee.

The owners couldn’t have been more thrilled. “They were blown away”, says Tony. “They had no idea what I was going to do beyond the store name.”

Tony’s original concept was to incorporate the store’s name, and then add some green grass to represent a golf course. But when you have a golf course, you have to have water hazards and sand traps. And you can’t play golf without a club, ball and tee. So the design kept evolving and growing as Tony used his imagination.

impact golf tony angell 012

To create the intricate shapes in multiple colors, Tony used various techniques and careful planning:

While other areas were pre-formed with foam, to create the blades of grass, Tony first cast that area in solid black, then used a dremmel to etch the blades, then filled them in with green grout.
He filled in the white areas last so that other colors wouldn’t bleed into it during processing.
The letters had to be put in the form upside down and backward, so Tony triple-checked his layout to make sure he had not reversed a letter.
Tony designed the lettering on a computer, printed the letters out on paper, then stuck them to ½” foam and drew outlines on the foam. He cut the foam on a scroll saw and carefully smoothed the edges with a sander. (This is similar to the way I created the CCI monolith described in this article.)

All of this required probably three times more thought, planning and work than a plain black countertop, but the results are orders of magnitude more impactful. Now Tony has an amazing showpiece in a store trafficked by golf enthusiasts such as doctors and lawyers. He has some extremely happy clients who will enthusiastically recommend him, plus display his business cards and brochures on the counter.

Best of all, he got himself and his wife a set of custom golf clubs in the deal. I’m sure he’ll put them to good use, and he can even do some networking on the golf course.

impact golf 013

Rebar in a cast in place concrete countertop

Posted on November 1, 2011 by Jeff Girard

I recently got the following question regarding my blog post “Mix design for cast in place concrete countertop in Cayman“:

Q: What is the size of the rebar? Where was it placed in the slab?

Here is what the rebar looked like:

rebar in gazebo

The rebar size and location were dicated by local practices (and the local structural engineer). While I know from practice (and from being an engineer myself) that the rebar used was grossly oversized, politics were the over-riding influence on the reinforcing schedule.

All the rebar was 1/2″ bar, located in the slab so that there was 2″ of cover measured from the top surface of the countertop. The 2″ cover depth is common where corrosion is an issue. Since this is an outdoor countertop on an island, corrosion is always a concern with concrete exposed to the elements.

Note that too little cover depth can lead to problems other than corrosion. See this article about rebar size in concrete countertops.

Relationship marketing pays off for Evolution Architectural Concrete

Posted on October 30, 2011 by Jeff Girard

by Lane Mangum, VP Business Services, The Concrete Countertop Institute

Dave Magnano of Evolution Architectural Concrete in Essex, CT recently completed a nice project in a contemporary lake house: white concrete countertops for three bathrooms and a kitchen. The 90 square foot project went smoothly and brought in about $9000.

lake house

While there were some technical challenges in coordinating all the details of sizes, reveals, and interaction with the custom cabinets, this was a relatively simple project. Although it was nicely profitable, it was not a huge project. And, the slabs were all the same basic color. The results were beautiful in their simplicity:

Dave Magnano 114

Dave Magnano 101

Dave Magnano 105

Subtle details called for careful craftsmanship. For example, the marine edge on the bathroom vanities required a lot of hand work to look good.

Dave Magnano 104

Dave Magnano 112

Besides the fine craftsmanship, what made this project remarkable is the relationships around it. Dave got the project after he met the architect at a LEED certification course. That one short meeting, and followup with samples, resulted in a $9000 project.

The relationships don’t stop there. While doing the project, he met a builder, a kitchen designer, a custom cabinet maker and a decorative plumbing and hardware (DPH) store owner. He’s already planning a display for the kitchen designer’s showroom, and he is meeting with the DPH owner about a display soon.

This project illustrates how important it is to get out and meet building and design professionals. Attend courses. Call an architecture firm and present a lunch and learn. Take samples to a kitchen design showroom. And with any project, be aware of the relationships you are building and actively work those relationships to build more business.

This is what I refer to as “relationship marketing” and what I teach in my self-study course Sales & Marketing 101. I’m so proud of Dave for hitting the jackpot with this perfect example of relationship marketing at its finest!

Dave has received extensive training in multiple techniques from The Concrete Countertop Institute, attending Precast in 2009, GFRC in 2010 and Advanced in 2011. He is also an active member of the Guided Success program which provides personal support directly from Jeffrey Girard, president of The Concrete Countertop Institute. Combined with Dave’s business savvy and quality craftsmanship, this makes Evolution Architectural Concrete one of the premier sources for concrete countertops in New England.

Evolution Architectural Concrete is a trade name of Trident Builders, LLC, and more information and photos can be found at www.TridentBuildersLLC.com. You can reach Dave at (860) 227-7325 or Dave [at] TridentBuildersLLC.com.

Do pozzolans and CSA cements work together in concrete countertops?

Posted on October 27, 2011 by Jeff Girard

In short, no.

There is still a lot of confusion, even several years after CSA cements became popular in concrete countertops. The simple, chemical fact is that CSA cements do not produce calcium hydroxide, so pozzolans have nothing alkaline to activate them.

CSA additives are different. Materials such as the brand Qwix® must be blended with portland cement. Therefore, the basic chemistry and the side effects that stem from using portland cement are inherited. Pozzolans can be used, and are dosed based on the portion of portland cement used in the concrete.

While it’s possible to make strong, rapid setting concrete using Qwix® , portland cement and pozzolan, this requires three ingredients, ingredients that each need to be sourced, shipped, dosed and weighed. I prefer simply to use a true CSA cement such as CTS Rapid Set® .

To test the interaction of a true CSA cement and pozzolans, in 2008 I performed compressive strength tests on a variety of concrete mixes that used Ultimax brand CSA cement and VCAS pozzolan. The cylinders were prepared according to ASTM C192 standards and tested by an independent concrete testing laboratory. Three different concrete mixes were made with Ultimax cement where 20% of the cement was replaced by VCAS.

Test results showed that all of the mixes had a 30% loss in 1- and 7-day compressive strengths versus mixes that used only Ultimax CSA cement. Rather than getting the strength increase seen with pozzolans and portland cement, you get a strength decrease.

Bottom line: Don’t use pozzolans with CSA cements.

VCAS strength tests

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